Motivated by the fact that the financial structure of export firms which have been known as leading firms in Korea is worsening due to the recent rise in domestic interest rates, this study examines effects of an increase in marginal firms in industries from 2006 to 2019 on productivity of exporting firms. As a result of the study, we found that the productivity of exporting firms decreased in an industry where the proportion of marginal firms increased. Also, as the proportions of marginal firms in industries increases, the entry rates as well as the exit rates of exporting firms slowed down and this trend is associated with the decline in the productivity of exporting firms.